Abstract
Channel spacing halving and multi-channel apodisation of sampling fiber Bragg grating (SFBG) based on moire effect are demonstrated, which are realized by stretching and double exposure in fabrication of the SFBG. The experiment and theoretical analysis showed that the channel spacing could be halved when the period of moire grating was four times of the period of sampling and the initial phase difference of two exposures was even times of π. The multi-channel apodisation could be realized when the period of moire fringe was twice the length of SFBG and the initial phase difference of two exposures was odd times of π. A novel method to control the initial phase difference of two exposures is presented in this paper. Usingthis technique, we fabricated two SFBGs with channel spacing of 50 and 100 G by a same phase mask and an apodized SFBG with channel spacing of 100 G.